METHOD AND APPARATUS FOR DETERMINING FORMATION RESISTIVITY AHEAD OF THE BIT AND AZIMUTHAL AT THE BIT

摘要

A method and apparatus for obtaining a resistivity measurement of an earth formation surrounding a borehole in an MWD device uses the drillbit and the adjacent portion of the drill collar as a focusing electrode for focusing the measure current from a measure electrode on the face or side of the drillbit. This provides the ability to see ahead of and azimuthally around the drillbit.